Controller 2: Feedback

(Note that not *all* effects follow the canonical allocation of 1: Camera, 2: Feedback, 3:Boingy/Psychedelia and
4: Tunnel but many do - we'll find examples that illustrate each controllers' function).

The first thing we need to do is get an understanding of what feedback actually *is*. It's actually one of
the most powerful things for changing the overall look of an effect and the best way to understand it
is to have a bit of a play with it.

Set up your xbox with two controllers, then use controller 1 to navigate to this effect:

Then pick up controller 2 and let's explore the basics of Feedback.

The basic technique of Feedback is something that I've been using since the old JagVLM and Tempest 2000 days,
and the way it works is that instead of clearing the screen each frame to draw the scene, what you do instead
is draw the *previous frame* instead. Normally you do this with some modification - for example you might
scale the previous frame up a bit, and draw it at a lesser intensity than it was originally. If you do that
then what you see is that objects in the scene appear to emit a kind of "smoke" or "glow" that
radiates out from the centre of the screen. (Things can be a bit more complex in Neon because the feedback can apply
only to certain *layers* (which we call "stacks") of the effect, and the feedback can be filtered or
nonlinear, but the principle is basically the same, and this effect is a handy one to explore it.

What the feedback controller does is allow you to control on the fly the transformations that get
applied to the previous frame when it's redrawn to the scene. You can control the Intensity (the brightness when
it's redrawn), the Scale (the amount by which it is stretched or shrunk, in both the X and Y directions)
and the Rotation (the amount by which the previous frame is rotated around its middle when it's drawn).

Pick up controller 2 and have a play with the right analog stick whilst watching the effect.
Your vertical axis on that stick controls the intensity (Up to increase, Down to decrease),
and the horizontal axis controls the rotation. Play around a bit and notice that with the
stick pushed fully up you're almost overloading the effect, causing it to go almost fully
to white; when that happens, ease down on the stick to back off the intensity a little.
Play with the rotation too and notice the swirly vortex-style effects that appear.

When you're happy that you can see what is happening there, try introducing movements of
the other stick. Push the left analog stick all the way up and to the right, whilst
continuing to adjust the intensity and rotation with the left stick. What you are doing
there is pushing both the X and Y scale way down to their smallest values, with the
result that all the feedback gets "sucked in" towards the middle of the effect.
You should see that the feedback stuff gets sucked down into clearly visible quadrants
of the screen, and those quadrants fill up with intricate, receding details.
Hold that position on the left stick and continue to explore with the right
analog stick to see what happens.

Next try opening up the X-axis scale of the feedback layer - keep the left analog stick
pushed up, but lean it all the way to the left instead of the right. Notice how, when the
rotation is close to zero, you'll get a long, horizon-type line with lots of horizontal
striations that will tend to divide the screen - this is due to setting maximum
scale horizontally whilst having minimum scale vertically. Keep playing with the intensity
and rotation, then just have fun and explore around all the settings freely. If you
get confused and "lose" what you're doing, push the left stick
all the way up and right then ease down gently on the intensity (Y axis of right analog
stick) if it's overdriving, or up gently if it's not bright enough, until you
see the complex structures emerge. Then rotate the feedback gently until you get
squared up. Just like the camera, if you let go of the controller, the automatic
controls will take over and straighten things up for you anyway.

Those are the basic controls of Feedback, but it isn't just those which make the
effect so powerful .

In the mode with which you've been playing, when we do the feedback, all we've
been doing is simply copying the previous screen with some geometrical changes
applied (plus intensity, of course). But there are many different ways we can
copy the previous screen apart from just a straight copy and intensity change.
In fact *anything* that gets drawn in Neon can be drawn through a variety
of what are called "pixel shaders", which can affect what is drawn
in many different ways. They can introduce distortion, or change the colours,
or blend with or filter through another image, or do a variety of things.
Some of them don't do that much when used in feedback but others can make a
big difference to what you see.

You can use the d-pad on controller 2 to change the shader usage on the
fly. Press the d-pad right to step one shader "up", or press
it left to step one shader "down". There are 26 different shader
settings in there. Step through them and explore them in the same way as
you did with the straight copy shader we started with, and observe the
different kinds of thing that can happen.

When you're happy with changing shader and exploring the resultant effect,
try using the d-pad on controller 1 to explore all of the effects in the
matrix, then play with the feedback settings in each effect using controller 2.
(You may find that some effects don't use feedback, in which case the
controller will do something else, or that the feedback isn't in the primary
layer - we'll explain more about layers when we cover the next controller
- but most effects should have some feedback in them). The easiest way to see
what the feedback controller is doing is to begin with the right analog stick
pushed all the way up (maximising the intensity of the feedback effect)
and switch between the shaders using the d-pad. Once you have a handle on
"where it is" you can begin to explore and play.

Some tips for controller 2

- Explore gentle intensity changes. In some of the feedback effects, the most
"interesting" zone to explore is right where the the intensity tips
over the threshold between normal and "overdriven". You'll know
that zone when you find it - try just delicately adjusting the feedback right
around that zone, and play with the other parameters as you do so.
The results can be very interesting.

- Explore scale-down and uneven-scale feedback. When the scale of both axes
is small, or one is small and the other not, you tend to get the most
interesting and intricate detaisl in the feedback, with all kinds of
fractal-looking structures emerging from the feedback.

- Do explore the shaders. Certain shaders and settings can yield a much more
"chaotic" style of effect than is the norm for Neon's
default effects which can be quite interesting.

- If you explore enough around, you may discover the signature logo of a beast... }:-)